My understanding is that if all you are swapping over is the centre on your 1000 diff then you either need a 1000 or 1200 diff centre (H145).
 
If you swap to the larger 120y centre (H150) you will need to either buy or make up a 2mm spacer to fit between the centre and diff housing.
 
Do you know which diff ratio are you currently running?
 
I've got a spare 1000 centre at home.
Can look at ratios tonight.
 
I'd guess that I have an h145 with 4.11 ratio and am on the gold coast.

G'day beetwenty, apparently if the H165 diff is out of a van with the 1200 engine it will fit in the 1000 housing, the H150 will fit with the spacer but they don't have the right ratio's, mine is a stock 1000 diff so it will be a 4.111, I've also read that the B20 wagon has a 4.375 ratio which would suit my needs, all this stuff is like rocking horse shit though so i'm just going to have to be patient.

weird error 

weird error 

weird error 

Ok so what i've worked out so far: a mechanic mate told me the diff from an early vannette would fit but so far i've found no information to say there even was a different diff in the early ones and they all had H165's that won't fit, H150's will fit with a spacer but the ratio's are too tall for what i need same with Datsun 1200, it seems like my only option is a diff centre out of a 1000 VB10 wagon which has a ratio of 4.373, also i can't fit a whole later diff in as my wheels are already at the limit of the gaurds, please correct me if i'm wrong here and any advice from people who have changed diffs would be appreciated, thanks Pedro.